Thermal wire stripper



March 1, 1966 T. E. TRETHEWEY ETAL 3,237,489

I THERMAL WIRE STRIPPER Filed Jan. 27, 1964 2 Sheets-Sheet 1 (@glHHlll /1 L; g I, Ill. 1 hug J7 March 1, 1966 T. E. TRETHEWEY ETAL 3,237,439

THERMAL WIRE STRIPPER Filed Jan. 27, 1964 2 Sheets-Sheet 2 M!!! II I N VEN TORS 76 04/41 1 7166' 77/6714 V ark) 5 fir/0 United States Patent 3,237,489 THERMAL WIRE STRIPPER Thomas E. Trethewey, Sycamore, and Roger E. Rinaldi,

De Kalb, Ill., assignors to Ideal Industries, Inc., Sycamore, 111., a corporation of Delaware Filed Jan. 27, 1964, Ser. No. 340,386 11 Claims. (Cl. 81-95) This invention relates to a thermal wire stripper and particularly to a thermal wire stripper having a sequence of movements for thermally severing each side or half of the 'wire insulation and then moving the wire to a position away from the heater elements so that the wire may be removed without contact with a heated area.

Another purpose is a wire stripper of the type described in which the wire to be stripped is moved successively, and by continued application of pressure, to a first position in which it is clamped and in which one side of the wire is in contact with a heater element, to a second position in which the clamped wire is moved so that the opposite side is in contact with a heater element, and a third position in which the clamped wire is spaced from the heater elements so that the wire may be removed from the severed slug of insulation.

Another purpose is a positively operating and reliably constructed thermal wire stripper of the type described.

Another purpose is a thermal wire stripper of the type described including improved means for removing the severed slug of insulation without causing contact between the stripped end of the wire and the heater elements.

Another purpose is an improved method of thermally stripping a wire which prevents contact between the stripped end of the wire and the heat areas.

Other purposes will appear in the ensuing specification, drawings and claims.

The invention is illustrated diagrammatically in the following drawings wherein:

FIGURE 1 is a side view of a wire stripper of the type described,

FIGURE 2 is a top plan view of the wire stripper illustrated in FIGURE 1,

FIGURE 3 is a vertical section of the stripper illustrated in FIGURES 1 and 2, with the stripper in the initial position for stripping a wire,

FIGURE 4 is a vertical section, similar to FIGURE 3, illustrating the first movement of the stripper in stripping a wire,

FIGURE 5 is a vertical section, similar to FIGURES 3 and 4, illustrating the second movement in stripping a wire,

FIGURE 6 is a vertical section, similar to FIGURES 3, 4 and 5, illustrating the third movement in stripping a wire, and

FIGURE 7 is an enlarged end view of the stripper described herein.

As illustrated in FIGURES 1 and 2, the stripper may include a pair of handle members 10 and 12 which are pivoted together, as at 14. Clamping members 16 and 18 extend outwardly from the pivotal handle members, with each of the clamping members having inturned gripping jaws 20 and 22, respectively. Preferably the gripping jaws are serrated, or formed with teeth, or otherwise constructed to firmly grip the wire to be stripped. One of the clamping members, in this case clamping member 16, may have an adjustable wire stop 24 having a wire stopping portion 26 which extends into the area between the clamping members.

A heater element 28 may be mounted on heater support rods 30 with the rods 30 being connected to an electrical cord indicated at 32. The rods may be fixed to one of the handle members, in this case the lower handle member 3,237,489 Patented Mar. 1, 1966 12. A heater rod mounting is indicated at 31 in FIGURE 7. The heater support rods 30 are electrically conductive, or in the alternative, they may have insulation on the outside and a wire on the inside. There may also be external wires providing power to the heater 28. In any event, electrical power is carried by the support rods 30 to the heater element 28.

As illustrated particularly in FIGURE 7, the heater element 28 may have an opening at one side and two spaced contact areas 34 and 36, shaped to receive a wire, and connected by a bridge 38. The contact sections 34 and 36 and bridge 38 may have a smaller cross sectional area than the remaining portions of the heater to provide high resistance and hence high heat. The heat provided by the heater will be concentrated at the contact areas 34 and 36 where thermal severing of the wire insulation takes place. Screws or the like 40 may connect the heater element to the support rods 30.

Clamping members 16 and 18 may be pivoted, as at 42, to lower handle member 12. There are various pressure applying mechanisms between the handle members and the clamping members which provide a sequence of clamping member movement described more fully hereinafter. A coil spring or the like 46 may be seated on a projection 48 on clamping member 16 and may be seated at its other end on a projection 50 mounting an adjustable set screw 51. A second coil spring 52 may be seat-ed at one end on a projection 54 on lower clamping member 18 and at the other end within a socket 56 formed by projection 58 on the upper handle member Iii. A set screw or the like 60 may be used to adjust the pressure on spring 52. The stop 62, again in the form of an adjustable set screw, may extend inwardly from a projection 64 on upper handle member 10. A third coil spring 66 may be fixed to lower handle 12 by a projection 68, and to clamping member 18 by a projection 70.

In operation, a wire to be stripped, for example as illustrated at 72 in FIGURES 36, is either passed through the front of the heater element or is slid through the open side. The wire is angled in so that its end abuts wire stop 26. The initial position of the wire, prior to stripping, is illustrated in FIGURE 3. Pressure is then applied to the handle elements to squeeze them together, generally the operator using one hand to perform the operation. The clamping jaws will move toward each other and generally simultaneously as they come into clamping relation with the wire to be stripped the wire will be placed in contact with lower heater area 36. Springs 46, 52 and 66 are eflective to move the clamping jaws into the position of FIGURE 4 as the handle elements are squeezed together. Spring 46 places downward pressure on clamping member 16 and spring 52 pivots lower clamping member 18 in a clockwise direction to move its jaw 22 toward jaw 20. Spring 66 provides pressure counter to spring 52 to control movement of the clamping members. In the first position one side of the wire insulation is thermally severed by operation of heater section 36.

Subsequent and continuous squeezing pressure on the handle members moves the stripper to the position of FIG- URE 5. The clamping jaws have now moved the wire from contact with heater section 36 to contact with upper heater section 34. Now the other side of the wire insulation will be thermally severed. This second movement is provided by continued pressure by springs 46 and 52. Spring 46 maintains the upper clamping jaw fast against the wire and spring 52 provides sufficient upwardly directed pressure to not only maintain a clamping position with the wire, but to move both clamping members in an upward direction.

Once both sides of the wire insulation have been thermally severed, continued pressure on the handles will move the clamping jaws to the position of FIGURE 6 in which the wire is out of contact with both heat areas 34 and 36. Stop 62 properly positions the jaws in this third position so that they are intermediate the two heat areas and generally centrally located between them. In moving from the position of FIGURE 5 to the position of FIG- URE 6 note that spring '46 is suificiently compressed so that screw 51 exerts downward pressure sufiicient to overcome the upward pressure provided by spring 52. Once the wire is out of contact with the heat areas the wire may be removed, leaving the severed slug of insulation between the jaws.

The use, operation and function of the invention are as follows:

A thermal wire stripper of this general type is illustrated in Patent 3,107,287. In the stripper of that patent, the wire completes a sequence of movements in contact with one of the heater elements. The present invention is specifically designed as an improvement over this wire stripper in that the sequence of movements under continued application of increasing pressure ends up with the wire positioned out of contact with the heater elements and after complete thermal severing of the insulation. The wire may then be pulled out of the stripper with the slug of insulation remaining in the clamping jaws. This has the advantage of enabling the wire to be removed without any contact with the heater elements. There will be no buming, nicking, scratching, scoring or other damage to the bare end of the wire. This is particularly important when the wire is to be used in a complicated apparatus such as a missile or the like, in which minute damage to the wire could cause a malfunction of the entire system.

The stripper is simply constructed, with the handle preferably formed of plastic and formed for easy gripping by one hand of the operator. A continuous squeeze by the operator will provide the pressure necessary to move the clamping jaws through the positions described, namely, first to a wire clamping in which one side of the wire is positioned against one of the heater contact areas, second to a position in which the clamped wire is placed against the other heater contact area, and third to a position in which the clamped wire is intermediate the heater contact areas so that the wire may be removed with the slug of insulation remaining between the clamping jaws.

The pressure applying mechanisms may take a variety of forms, although it is preferred to use coil springs which are seated against and held by the handles and the clamping jaws. A stop is used with the stop being adjustable so that the final position of the wire relative to the heater area may be adjusted. It is important to have the pivot points of the jaws spaced and to have the pressure application points so located that the sequence of movements described above may be accomplished by continuous squeezing pressure on the handle members.

Adjustment screws 51, 60 and 64 are effective to vary the position at which the jaws come together in a clamping position as well as the extent of up and down movement of the clamped jaws. These screws are thus efiective to set the tool for stripping many diiferent wire sizes.

The dwell time at each heater contact area is easily controlled by the operator as he may momentarily pause at any time during the application of manual pressure.

Whereas the preferred form of the invention has been shown and described herein, it should be realized that there are many modifications, alterations and substitutions 'said heater, and means for applying pressure to said clamping means to move said clamping means successively and by continued application of increasing pressure, first to a wire clamping position in which the wire is in contact with one of said spaced heater areas, second to a position in which the clamped wire is in contact with the other of said spaced heater areas, and third to a position in which the clamped wire is positioned out of contact with and intermediate said spaced heater areas.

2. The structure of claim 1 further characterized in that said spaced heaterareas are disposed on opposite sides of the wire to be stripped.

3. The structure of claim 1 further characterized in that the means for applying pressureto said clamping means include pivotal handle members at least partially enclosing said clamping means.

4. The structure of claim 1 further characterized in that said clamping means include a pair of pivotal jaw members extending within the means for applying pressure to said clamping means.

5. The structure of claim 1 further characterized by and including a wire stop positioned onsaid clamping means.

6. A thermalwire stripper including a pair of pivotal handle members, a heater having spaced areas shaped to thermally sever wire insulation, means attached to said handle members for supporting said heater, a. pair of pivotal wire clamping jaws at least in part within said handle members, and a plurality of yielding pressure applying means between said handle members and the clamping jaws to move said clamping jaws successively and by continued application of increasing pressure to said handle members, first to a wire clamping position in which the wire is in contact with one of said spaced heater areas, second to a position in which the clamped wire is incontact with the other of said spaced heater area, and third to a posit-ion in which the clamped wire is positioned out of contact with and intermediate said spaced heater areas.

7. The structure of claim 6 further characterizedin that in said third position said wire is generally equally spaced from said spaced heater areas.

8. The structure of claim 6 further characterized in that each of said pressure applying means includes a spring member, with one end of each spring member being seated on a'handle member and the other end being seated on a clamping jaw.

9. The structure of claim'6 further characterized in that there are three pressure applying means, one of said pressure applying means being positioned between and in contact with one of said handle members and one of said clamping jaws, the second pressure applying means being positioned between and in contact with said onehandle member and the other of said clamping jaws, the third pressure applying means being positioned between and in contact with the other of said handle members and-the other of said clamping jaws.

10. The structure of claim 6 further characterizedin that said clamping jaws are pivotally mounted to one of said handle members.

11. The structure of claim 10 further characterized in that there are two pressure applying means on oneside of said pivot point, and one pressure applying means on the other side of said pivot point.

References Cited by the Examiner UNITED STATES PATENTS 1,749,939 3/1930 Heller 29400 2,768,276 10/1956 Arntzen 81-95 3,107,287 10/1963 Schechter 8l9.5 3,116,545 1/1964 Brown 29403 3,139,777 7/1964 Gindoff 81-95 WILLIAM FELDMAN, Primary Examiner.

MILTON S. MEI-IR, Examiner, 

1. A THERMAL WIRE STRIPPER INCLUDING A HEATER HAVING SPACED AREAS SHAPED TO THERMALLY SEVER WIRE INSULATION, WIRE CLAMPING MEANS MOUNTED FOR MOVEMENT RELATIVE TO SAID HEATER, AND MEANS FOR APPLYING PRESSURE TO SAID CLAMPING MEANS TO MOVE SAID CLAMPING MEANS SUCCESSIVELY AND BY CONTINUED APPLICATION OF INCREASING PRESSURE, FIRST TO A WIRE CLAMPING POSITION IN WHICH THE WIRE IS IN CONTACT WITH ONE OF SAID SPACED HEATER AREAS, SECOND TO A POSITION IN WHICH THE CLAMPED WIRE IS IN CONTACT WITH THE OTHER OF SAID SPACED HEATER AREAS, AND THIRD TO A POSITION IN WHICH THE CLAMPED WIRE IS POSITIONED OUT OF CONTACT WITH AND INTERMEDIATE SAID SPACED HEATER AREAS. 